The invention relates in general to construction of industrial robots and in particular to a new and useful robot having a gripping device for gripping workpieces having particularly contoured engagement faces.
For gripping and clamping irregularly shaped workpieces with a fissured gripping surface geometry are used gripping devices with two exchangable molded jaws adapted to the shape of the workpiece. In order to prevent the form-locking gripping jaws from getting stuck at projecting or deeply recessed points of the workpieces during the opening and closing of the gripping device, the gripping jaws must always move parallel to each other over the entire gripping range. If the workpieces must be gripped and deposited without changing their position, the gripping jaws must also move uniformly toward and away from each other on a straight line extending perpendicularly to the plane of symmetry of the gripping device.
The Proceedings, issued on the occasion of the 8th International Symposium on Industrial Robots from 5/30-6/1/78 Stuttgart, show in vol. 1, p. 464, FIG. 6 a gripping device which is displaceably mounted on a guide rail secured on the housing of the gripping device and extending perpendicularly to its plane of symmetry. The fingers are displaced in opposite directions by means of two toggle lever gears so that the gripping jaws move in a straight line toward and away from each other parallel and in a constant distance from the housing of the gripping device. This gripping device, however, has the great disadvantage that it required much space, even with a relatively small gripping range, due to the use of a straight guide rail.
From DOS No. 2 257 609 is known a gripping device with two gripping jaws, where each gripping jaw is arranged on the coupler of a parallel crank gear and one crank each of the parallel crank gear is connected with a common driving mechanism for moving the gripping jaws in opposite directions. The parallel crank gears also permit a space saving design of the housing of the gripping device, even with a wide gripping range. But the couplers and gripping jaws, which are always parallel to each other, move on a curved track, their distance from the housing varying in dependence on their distance from each other. This gripping device can therefore, not receive and deposit the workpieces to be handled without displacement.